This is a legacy version of the WELL Building Standard. Please check the latest version here.

Circadian emulation

P3. Circadian emulation

This feature manages the spectral power distribution of light over the day to more closely resemble the solar cycle. The power of home lighting can be strengthened by automating the selection of light type according to the time of day. This feature uses the equivalent melanopic lux unit defined earlier in this chapter.

Many animals evolved to adapt to the diurnal cycle by using light as a cue for activity and rest. Subtle changes in light quality over the day help modulate the intensity of activity, levels of alertness and preparation for sleep.

Part 1: Circadian Lighting

In all bedrooms, bathrooms, and rooms with windows, the lighting system meets the following requirements:

a. Allow users to set a "bed time" and a "wake time".
b. If lights are turned on in the interval spanning "wake time" and 2 hours before "bed time", they provide a maintained average of at least 250 equivalent melanopic lux.
c. If lights are turned on in the interval spanning 2 hours before "bed time" and "wake time", they provide a maintained average of 50 equivalent melanopic lux or less.
Part 2: Dawn Simulation

In all bedrooms, the lighting system or a standalone device meets the following requirements:

a. Allow users to set a "wake time".
b. Gradually increases light (as measured at the bed, viewing the light) from 0 to at least 250 equivalent melanopic lux over the course of 15 minutes or longer.

Applicability Matrix

Commercial Kitchen Education Multifamily Residential Restaurant Retail
Part 1: Circadian Lighting - - O - -
Part 2: Dawn Simulation - - O - -

Verification Methods Matrix

Letters of Assurance Annotated Documents On-Site Checks
PART 1 (Design)
Circadian Lighting
Visual Inspection
PART 2 (Design)
Dawn Simulation
Architect